METHOD AND DEVICES FOR VALIDATING A TRANSACTION DURING RADIO COMMUNICATION

Description

Field of invention

[0001] The invention relates to short-range wireless communications for transmitting data between two devices via the human body. More specifically, the invention relates to a system for carrying out transactions between a terminal worn by a user and a communication device such as a base station or a reader, connected for example to a transaction server, by using the conductivity capacity of the human body to transmit the electromagnetic waves carrying such wireless communications. Prior art

[0002] Near field communications, commonly known as "NFC" (for "Near Field Communication"), based primarily on the ISO (International Standard Organization) 14443 standard, use wireless technologies to enable the exchange of information between two devices located a short distance apart, typically less than ten centimeters. Communications of this type offer numerous applications, for example in the fields of payment or transportation. The near field receiver receives a message from the near field transmitter. Such a message may correspond, in the aforementioned context, to the validation of a transaction such as, for example, the exchange of a ticket (for an event, transportation, etc.), a payment, the launch of a personalized service on a computer, a television, access to a room, etc.

[0003] A system for exchanging such messages is known in the prior art, in which the receiver is contained in a terminal worn by a user, the messages being received by the receiver during an intra-body communication via the user of the terminal. An intra-body communication uses the conductivity capacity of the human body to transmit electromagnetic waves carrying wireless communications. Such technology is called IBC (for "Intra-Body Communication" in English).

[0004] Such a wireless communication system is for example described in document WO2012 / 131224. The system comprises a terminal worn by a user, the antenna of which is directly in contact with, or very close to, the user. A signal emitted by the terminal is modulated by means of a low-frequency modulator and transmitted through the user's body. It is indeed known that the human body has conduction capacities suitable for conveying such electromagnetic signals as long as the antenna is located close (less than a few centimeters) to the user's body and designed so as to achieve the expected objective. The antenna is made up for this purpose of a set of turns in an adequate number and arrangement to optimally emit the wave through the human body.This system according to the state of the art also includes an NFC communication device comprising a receiver which includes a sensitive surface consisting of an antenna of the same type as that of the transmitter and on which the user can make a gesture of approach, for example placing the hand on the antenna, touching it or simply bringing the hand close to the antenna a few centimeters from it. The NFC communication device receives the signal due to the physical contact, or at least the proximity, of the user with the antenna. The received signal is demodulated and transmitted to suitable equipment to carry out processing, in this case to implement the transaction (payment, door opening, etc.).

[0005] In order to secure this type of transaction, document WO2016 / 001506 proposes to detect and validate a voluntary approach gesture by the user, in order to ensure that the approach gesture is actually performed. Such a technique is also described in document WO 2019 / 063902.The disadvantage of such a system lies in the fact that in the presence of several communication devices located near the user's terminal, even if the user makes a voluntary approach gesture in relation to a first communication device, but not in relation to a second communication device, the transaction may fail, in the case where the signal received by the user's terminal by intracorporeal communication, coming from the second communication device, has a higher power than that of the signal characterizing the voluntary approach gesture of the user, received by intracorporeal communication from the first device.

[0006] In fact, it is the frame contained in the signal emitted by this second communication device which will be decoded by the user's terminal and not the data frame contained in the less powerful signal characterizing the user's approaching gesture, as emitted by the first communication device.

[0007] Thus, the user's terminal will be able, via a dedicated application, to detect the user's voluntary approach gesture in relation to the first communication device, by analyzing the evolution of the envelope of the NFC signal received, but risks associating this envelope erroneously with an approach to the second communication device in connection with the decoding of the frames received from the latter.

[0008] The transaction between the terminal and the first communication device will therefore not be able to be completed. Subject matter and summary of the invention

[0009] One of the aims of the invention is to remedy drawbacks of the aforementioned state of the art.

[0010] To this end, an object of the present invention relates to a method for receiving a signal during an intracorporeal communication via a user carrying a terminal, comprising the following, at the terminal: receiving from a communication device a signal characterizing that the user has made a gesture of approaching the device between two instants, detecting in the received signal a first frame of radio data generated between the two instants, said first frame being at the same frequency as that of the received signal,

[0011] Such a method is remarkable in that it includes the following, at the terminal level: detecting in the received signal a second frame of radio data generated between the two instants, said second frame being at a frequency different from that of the received signal, comparing the first frame to the second frame, validating a transaction depending on the presence or absence of information common to the first and second compared frames.

[0012] Such a reception method according to the invention allows the terminal worn by the user to establish a correlation between the first radio frame of the signal received, characterizing that a gesture of approaching the user with the device was made between two instants, and the second radio frame received at a frequency different from this signal, to deduce therefrom that validation information for the transaction to be established is communicated to it by the device in connection with the approach gesture.

[0013] The reception method according to the invention thus allows the terminal worn by the user to check, among the data frames that it receives via intracorporeal communication, from several communication devices located near the terminal, whether or not one of these devices has been approached (or touched) by the user to carry out a transaction, and to validate a transaction, via the communication device that the user has actually approached or touched, by determining at least one piece of information common to the first and second frames or, on the contrary, to refuse the transaction, in the case where the terminal does not determine any information in common between the first and second frames.

[0014] The invention thus makes it possible in a very simple manner, by modifying a conventional signal characterizing that the user has made a gesture of approach, by adding the second radio data frame, to verify by a terminal carried by the user, which device has actually been approached or touched by the user of the terminal to implement a transaction. Furthermore, by correlating this common information close in time to the time interval between the two instants which characterizes that the user has approached or touched the device, the terminal is able to recognize with a good probability, which is, among the communication devices which are located near the terminal, the communication device via which a transaction must be established.

[0015] Intrabody communication is a communication that uses the conductivity of the human body to transmit electromagnetic waves that carry wireless communications. Such technology is called IBC.

[0016] According to a particular embodiment, said at least one piece of information common to the first and second frames is an identifier or location information of the communication device.

[0017] Thanks to the fact that the first and second radio frames containing the common information were generated in parallel between the two instants corresponding to the time interval during which the user approached or touched a communication device, the terminal is able to correlate, very simply and without requiring complex computing resources, the identity or location of the device that was actually approached or touched.

[0018] According to another particular embodiment, the common information is represented in binary form.

[0019] The binary representation of the information determining whether the user has approached or touched the device or not allows to reduce the signaling cost of transmitting radio data frames between the communication device and the terminal.

[0020] According to another particular embodiment, the second frame is detected several times between the two instants.

[0021] Such an arrangement allows the terminal to implement several comparisons between a first radio frame and a second radio frame, so as to distinguish with the best possible probability which device was actually touched or approached by the user.

[0022] According to another particular embodiment, the second frame is detected once between the two times and is representative that between the two times, the user touched the communication device.

[0023] Such an arrangement corresponds to an embodiment for which the user must touch the communication device to implement a transaction and not simply approach the device.

[0024] The various embodiments or features mentioned above may be added independently or in combination with each other to the reception method defined above.

[0025] The invention also relates to a terminal having intra-body communication capabilities via a user carrying said terminal, said terminal comprising a processor which is configured to implement the following: receiving from a communication device a signal characterizing that the user has made a gesture of approaching the device, between two instants, detecting in the received signal a first frame of radio data generated between the two instants, said first frame being at the same frequency as that of the received signal.

[0026] Such a terminal is notable in that the processor is configured to implement the following: detecting in the received signal a second frame of radio data generated between the two instants, said second frame being at a frequency different from that of the received signal, comparing the first frame to the second frame, validating a transaction depending on the presence or absence of information common to the first and second compared frames.

[0027] Such a communication terminal is in particular capable of implementing the aforementioned reception method.

[0028] The invention also relates to a method for transmitting a signal during an intra-body communication via a user carrying a terminal, comprising the following, at a communication device: detecting a gesture of approaching the user with the communication device, said gesture being performed between two instants, transmitting to the terminal a signal characterizing the approaching gesture, said signal containing a first radio data frame generated between the two instants, said first frame being at the same frequency as that of the transmitted signal. Such a transmission method is remarkable in that the transmitted signal further comprises a second radio data frame generated between the two instants, the second frame being at a different frequency from that of the transmitted signal.

[0029] According to a particular embodiment, said at least one piece of information common to the first and second frames is an identifier or location information of the communication device.

[0030] According to another particular embodiment, the common information is represented in binary form.

[0031] According to another particular embodiment, the second frame is generated several times between the two instants.

[0032] According to another particular embodiment, the second frame is generated once between the two times and is representative that between the two times, the user touched the communication device.

[0033] The various embodiments or features mentioned above may be added independently or in combination with each other to the emission method defined above.

[0034] The invention also relates to a communication device having signal transmission capabilities during intra-body communication via a user carrying a terminal, said device comprising a processor which is configured to implement the following: detecting a gesture of approaching the user with the communication device, said gesture being performed between two instants, transmitting to the terminal a signal characterizing the approaching gesture, said signal containing a first radio data frame generated between the two instants, said first frame being at the same frequency as that of the transmitted signal. Such a device is remarkable in that the transmitted signal further comprises a second radio data frame generated between the two instants, the second frame being at a different frequency from that of the transmitted signal.

[0035] Such a device is particularly capable of implementing the aforementioned emission method.

[0036] The invention also relates to a computer program comprising instructions for implementing the reception or transmission method according to the invention, according to any one of the particular embodiments described previously, when said program is executed by a processor.

[0037] Such instructions may be stored permanently in a non-transitory memory medium of the communication terminal implementing the reception method or of the communication device implementing the transmission method.

[0038] This program may use any programming language, and may be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0039] The invention also relates to a recording medium or information medium readable by a computer, and comprising instructions of a computer program as mentioned above.

[0040] The recording medium may be any entity or device capable of storing the program. For example, the medium may include a storage medium, such as a ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a USB flash drive or a hard disk.

[0041] Furthermore, the recording medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention may in particular be downloaded from a network such as the Internet.

[0042] Alternatively, the recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to perform or to be used in performing the aforementioned receiving or transmitting method. Brief description of the drawings

[0043] Other characteristics and advantages will appear on reading particular embodiments of the invention, given as illustrative and non-limiting examples, and the appended drawings, among which: [ Fig. 1 ] there figure 1 represents a communication system according to an embodiment of the invention when a terminal carried by a user carries out a transaction with a communication device, in a particular embodiment of the invention, [ Fig. 2 ] there figure 2 represents a terminal in a particular embodiment of the invention, [ Fig. 3 ] there figure 3represents a communication device in a particular embodiment of the invention, [ Fig. 4 ] there figure 4 represents the main actions implemented in the signal transmission / reception method, according to a particular embodiment of the invention, [ Fig.5 ] there Figure 5 represents an embodiment of a signal representative of a gesture of approaching a user with a communication device according to the invention. Detailed description of an embodiment of the invention

[0044] There figure 1 represents a wireless communication system according to one embodiment of the invention.

[0045] Such a system includes: a terminal 1 carried by a user U, the terminal 1 being equipped with an NFC-IBC module (not shown) and an IBC antenna designated by the reference ANT1, a communication device 2, such as for example a base station, or terminal, equipped with an NFC module.

[0046] The terminal 1 according to the invention is adapted to transmit and receive radio signals, also called radio carrier waves, via the antenna ANT1, through the body of a user U. For this purpose, the terminal 1 is located close to the user U, without necessarily being in direct contact with the latter. For example, the terminal 1 is placed inside a pocket or bag carried against the user. In these configurations, it is estimated that the terminal 1 is not more than a few centimeters from the body of the user U. The distance is for example less than 10 cm. The terminal 1 is equipped with a battery or batteries, for autonomous operation. It is for example a mobile phone equipped with an NFC antenna used as an antenna to transmit and receive the modulated or unmodulated electrical signals. In the context of this exemplary embodiment, and as already explained previously, the NFC antenna ANT1 is also IBC.For this purpose, the ANT1 antenna is designed to optimally receive the electromagnetic wave through the human body. To do this, it is made up of a set of turns in the appropriate number and arrangement.

[0047] Terminal 1 can of course take other forms. For example, it can be any portable device capable of communicating in the near field with NFC transmitters, directly or via the human body (bracelet, electronic tablet, necklace, etc.).

[0048] The communication device 2 is a piece of equipment capable of transmitting and receiving radio signals, or carrier waves, in particular through the body of the user U, via an IBC antenna designated by the reference ANT2. In this exemplary embodiment, the communication device 2 is a reader which comprises a sensitive surface constituted by the antenna ANT2, possibly protected and adapted to react when the user approaches the antenna ANT2 within a few centimeters, for example by placing his hand above the antenna ANT2. Thus, when the user U approaches the antenna ANT2, with his hand for example, a modulated electrical signal transmitted or received via the antenna ANT2 is capable of being conveyed by the body of the user U. The antenna ANT2 may further comprise a sensitive surface SUT, shown in dotted lines on the figure 2, which is adapted to react when the user touches it, for example by placing his hand on it. Thus, when the user U touches the sensitive surface SUT, with his hand for example, a modulated electrical signal emitted or received via the antenna ANT2 is able to be conveyed by the body of the user U. According to an exemplary embodiment, the sensitive surface SUT can be provided with one or more capacitive detectors (not shown). Other touch detection technologies can of course be implemented, such as for example surface wave technology, infrared technology, etc. The communication device 2 also comprises a user interface (also called HMI) referenced IU, intended to display messages for the user and equipment (not shown in the figure 1) capable of performing processing, such as a PC or a server. The ANT2 antenna (in the case where a proximity is sufficient) or the sensitive surface SUT covering the ANT2 antenna (in the case where a touch is required), the user interface UI and the equipment are connected for example by means of a wired connection, or through a network, for example a mobile network, or the Internet network. The communication device 2 is configured to operate in IBC by loading a specific program (software), without modifying the hardware.

[0049] According to an alternative embodiment, the communication device 2 consists of an electronic shelf label (ESL) that the user touches in order to receive product personalization information (reduction, advantage, promotion, product information, etc.). Description of an embodiment of terminal 1

[0050] There figure 2presents the simplified structure of the terminal 1 adapted to implement the signal reception method which will be described below.

[0051] Terminal 1 is for example a mobile terminal of type smartphone adapted to implement the invention. According to another example, the terminal is a simple electronic card equipped with the following modules: a processing unit, such as a processor or "CPU" (for "Central Processing Unit"), referenced UT1, intended to load instructions into memory, to execute them, to carry out operations, a set M1 of memories, including a volatile memory, or "RAM" (for "Random Access Memory") used to execute code instructions, store variables, etc., and including a non-volatile memory of the "ROM" (from the English "Read Only Memory") type, or "EEPROM" (for "Electronically Erasable Programmable Read Only Memory") intended to contain persistent information, in particular the identification data of the user UT, an IBC module referenced MIBC1, including: an antenna ANT1 adapted in particular to receive signals on the radio channel and via the human body, so that a modulated electrical signal carried by the user's body is able to be received by the antenna, which is located in the terminal, in proximity to the human body;a demodulator DEMOD, intended to receive via the antenna ANT1 a modulated electrical signal and to transform it into a digital signal intended to be transmitted to the processing unit; the software components (firmware, etc.) necessary for implementing IBC communications; a radio module MR1 of Bluetooth or WiFi type intended to transmit in particular data in return from the terminal 1 to the device 2 or any other suitable device, preferably, and in particular if the following modules are not implemented on another device: a voluntary gesture detection module, referenced DGV, to analyze the signals received by the module MIBC1 and decide whether or not it is a signal SGV' corresponding to a movement comprising a voluntary gesture of the user U and modified according to the invention;an analysis module ANA for analyzing any signal received from the communication device 2, in particular following a voluntary movement of the user, and detecting in a time interval where the amplitude of the received signal is maximum, whether the received signal comprises a first frame of radio data received at the same frequency as the received signal and a second frame of radio data received at a frequency different from that of the first frame; a calculation module CAL for comparing the first frame with the second frame in order to detect the presence or absence of information common to the first and second frames; an application module APP for, depending on the presence or absence of this common information, validating or not the appropriate transaction required by the terminal 1, either with the device 2, or with any other appropriate device / equipment. ; Description of an embodiment of the communication device 2

[0052] There figure 3shows the simplified structure of the communication device 2 adapted to implement the signal transmission method which will be described below. The device 2 comprises several modules which are similar to those of the terminal 1 described in relation to the figure 2 : a processing unit, such as a processor or CPU, referenced UT2, used to execute code instructions, store variables, etc., a set M2 of memories, including a volatile memory or "RAM" (for "Random Access Memory") used to execute code instructions, store variables, etc., and a non-volatile memory, of the “ROM” or “EEPROM” type intended to contain persistent information, an IBC module referenced MIBC2, including: an antenna ANT2 adapted in particular to transmit / receive signals on the radio channel and via the human body and to react to a gesture of approaching the user U, for example by bringing the hand just above the antenna ANT2, said antenna ANT2 being arranged so as to cooperate with the processing unit UT2 to implement the steps of the signal transmission method which will be described later; a modulator MOD intended to adapt a digital signal produced by the processing unit UT2 into a modulated electrical signal, intended to be transmitted, via the antenna ANT2, through the user's body.The modulation operation performed by the modulator is for example an amplitude modulation: the signal is a frequency signal of for example 13.56 MHz, amplitude modulated with a modulation rate of approximately 10% (known characteristic of type B according to the NFC standard). The invention is however not limited to this type of modulation. In another exemplary embodiment, the modulation is a frequency modulation, less sensitive to interference, or a phase modulation; in the case where the approach gesture is a touch, a touch surface SUT adapted to react when the user U touches it (contact, light touch, tapping, etc.). In the example described here, this surface corresponds to the antenna, so that a modulated electrical signal emitted via the antenna ANT2 is capable of being conveyed by the body of the user who touches the surface SUT. In an exemplary embodiment, the antenna can be integrated into the surface.The surface is arranged so as to cooperate with the processing unit UT2 to implement the steps of the signal transmission method which will be described later; a radio module MR2 of the Bluetooth or Wi-Fi type intended in particular to receive data in return from the terminal 1 (signals received by the terminal 1, data relating to the transaction, etc.) and / or to come into contact with another device to validate the transaction (door, connected object, etc.), the software components (firmware, etc.) necessary for the implementation of the IBC communications, optionally a user interface (HMI) adapted to transmit instructions or information messages to the user U. For example, the user interface is a screen on which the messages and instructions are displayed.In another exemplary embodiment, the interface is an audio interface for playing messages and instructions, for example to indicate to the user that he can remove his hand from the surface. The interface may also include a keyboard, a microphone, etc. and in particular if the following modules are not present on another device, a frame generation module GTR for generating a first radio data frame TR1 at the same frequency as the modulated signal and a second radio data frame TR2 at a frequency different from that of the first frame, providing a signal SGV' corresponding to a movement comprising a voluntary gesture of the user U as modified according to the invention.

[0053] It is recalled that any commercial reader (for example an EPT for “electronic payment terminal”) can advantageously be used as a communication device 2, provided that it benefits from the MIBC2 module and possibly has a touch surface in the case where the transaction requires touching the device 2, and, after a simple update of the reader software (installation and / or update of the application and configuration of the NFC emission) to make it capable of transmitting a message having the characteristics (frequency, modulation, etc.) of IBC via its antenna. Description of an embodiment of a method for two-way wireless intrabody communication

[0054] In reference to the figure 4 , we now describe the progress of a method of bidirectional wireless communication through the human body of a user U, between the aforementioned terminal 1 and the aforementioned communication device 2, according to an embodiment of the invention.

[0055] In an initial step S0, in response to the approach of the user U to the device 2, the device 2 returns information to the user U. According to a particular exemplary embodiment, this may be an information message such as for example: “to validate the amount of the transaction, please bring your hand close to the antenna ANT2 / touch the touch surface SUT”, “to validate access to the library, please bring your hand close to the antenna ANT2 / touch the touch surface SUT”, etc. Such an information message may be returned textually and / or vocally.

[0056] The process then proceeds as follows: In S1, the device 2 transmits via its antenna ANT2 a modulated electrical signal of the NFC type associated with a search message intended for a device located near the device 2, in this case the terminal 1 carried by the user U. Such a signal, designated by the reference SIG on the figure 4, typically contains a default data frame as well as a payload containing, for example, a random number, a code, a key, etc. This frame constitutes a search message transmitted in the SIG signal emitted by the device 2 which is intended, according to this example, to come into contact with a portable device located near the device 2. It is specific to the transaction service offered: payment, access to premises, etc.

[0057] The SIG signal can be emitted continuously for a predefined duration.

[0058] At the end of this transmission duration, device 2 switches to reception mode.

[0059] In S2, the SIG signal transmitted in S1 is detected and received by terminal 1.

[0060] In S3, terminal 1 demodulates the received SIG signal into a digital signal.

[0061] In S4, terminal 1 analyzes, via the ANA module of the figure 2, the digital signal thus obtained. During this analysis, the terminal 1 detects at least one of the information elements corresponding to the interrogation of the device 2, namely in this example a service using IBC technology. Since the APP application does not detect at this stage any information relating to a voluntary gesture of the user U in relation to the device 2, the SIG signal is ignored by the terminal 1.

[0062] The method according to the invention then proceeds as follows: In S5, the user U touches the sensitive surface SUT of the device 2, for example by placing his hand on it, or approaches the antenna ANT2 of the device 2, for example using his hand.

[0063] In S6, device 2 generates an electrical signal SGV representative of the voluntary gesture of user U.

[0064] On the Figure 5 , the SGV signal includes: a first portion P1 characterizing the fact that the user U has not yet approached the antenna ANT2 / touched the touch surface SUT of the device 2. For this purpose, the power or amplitude of the signal SGV is low, for example of the order of -70 dB; a second portion P2 characterizing the fact that the user U has approached the antenna ANT2 / touched the touch surface SUT of the device 2. For this purpose, the signal SGV increases sharply until it reaches an amplitude of the order of, for example, -50 dB, at a time t1 max; a third portion P3 characterizing the duration during which the user U keeps his hand above the antenna ANT2 / remains in contact with the touch surface SUT of the device 2. For this purpose, the signal SGV reaches a maximum amplitude of the order of -50 dB up to a time t2 max; a fourth portion P4 characterizing the fact that at t2 max, user U has moved his hand away from device 2.For this purpose, the SGV signal decreases abruptly until it reaches an amplitude of the order of -70 dB.

[0065] Referring again to the figure 4 , if there has been a rapprochement or touch, the GTR module of device 2 generates in S7: -- a first radio data frame TR1 for validating the gesture of the user U which includes information INF characterizing for example the device 2, -- a second radio data frame TR2 for validating the gesture of the user U which includes the information INF.

[0066] Other information may be contained in the TR1 data frame, such as a service identifier and / or random data.

[0067] As a non-exhaustive example, such INF information is coded on one or more bits. Of course, the INF information could be presented in textual, alphanumeric, etc. form.

[0068] According to an exemplary embodiment, the INF information is an identifier of the device 2. Alternatively, the INF information is a location address (GPS coordinates, URL address, etc.) of the device 2.

[0069] Other information may be contained in the TR1 data frame, such as a service identifier and / or random data.

[0070] If there has been no approach or touch, the GTR module of device 2 generates in S7: -- the first radio data frame TR1 for validating the gesture of user U which was described above, -- a second radio data frame TR2 for non-validation of the gesture of user U which includes information INF' different from the information INF, for example information INF' containing an error code on for example one or more bits. Of course, the information INF' could be in a textual, alphanumeric form, etc.

[0071] In S8, device 2 modulates, via its MOD module ( fig.3 ), the SGV signal by associating with it, between the instants t1 max and t2 max, the frames TR1 and TR2, providing an SGV' signal.

[0072] In S9, the device 2 transmits via its antenna ANT2 a modulated electrical signal SGV' for validation or non-validation of the gesture of the user U, intended for the terminal 1 carried by the user U, said signal being associated, between the instants t1 max and t2 max, with the first and second frames TR1 and TR2 generated in S7. The frame TR1 is transmitted at the same frequency as that of the signal SGV', that is to say for example 13.56 MHz, while the frame TR2 is transmitted at a frequency different from that of the signal SGV'. Such a different frequency is for example of the order of a few kHz, for example 5 kHz.

[0073] According to one embodiment, a single frame TR2 is transmitted between times t1 max and t2 max, following a frame TR1.

[0074] As an alternative, as shown in the Figure 5 , a single TR2 frame is transmitted between two TR1 frames, in the time interval t1 max , t2 max . In the example shown, the two TR1 frames are separated by a time interval Δtr1 equal for example to 10 ms, while the TR2 frame is spaced by two successive TR1 frames, of the same time interval Δtr2 equal for example to 6.2 µs. A single TR2 frame is transmitted for example in the case where the device 2 is equipped with the touch surface SUT, at the moment when the user U touches the surface SUT of the device 2.

[0075] According to another embodiment, between the times t1 max and t2 max, the frame TR2 can be sent continuously, just like the frame TR1, whether or not the device 2 is equipped with a touch surface SUT.

[0076] At S10, the modulated electrical signal SGV' emitted at S9 is detected and received by terminal 1, via the body of user U, passing through antenna ANT1.

[0077] In S11, terminal 1 demodulates the received electrical signal SGV' into a digital signal, via its DEMOD module ( fig.2 ). For this purpose, terminal 1 demodulates the modulated electrical signal SGV' into the first data frame TR1 at a frequency of 13.56 MHz. Also at S10, terminal 1 demodulates the modulated electrical signal SGV' into the second data frame TR2 at a frequency of 5 kHz.

[0078] In S12, via its DGV module ( fig.2), the terminal 1 analyses the digital signal thus obtained in order to validate whether or not the gesture of the user U corresponds to a voluntary gesture on the part of the latter and whether or not the antenna ANT2 of the device 2 has been approached by the user U or whether or not the touch surface SUT of the device 2 has been touched by the user U, in the case where the device 2 is equipped with such a surface.

[0079] During this analysis, the terminal 1 detects in S120 that the amplitude of the signal SGV' is maximum between the instants t1 max and t2 max and that the signal SGV' has exceeded a predetermined threshold SP between these two instants. A first condition according to which the signal SGV' is representative of a gesture of approach of the user U with the device 2 is therefore fulfilled.

[0080] In S121, from the first frame TR1, the terminal 1 detects the information INF, and possibly the other aforementioned information, such as for example a service identifier and / or random data. Also in S121, or in a step simultaneous to S121, from the second frame TR2, the terminal 1 detects the information INF or the aforementioned information INF'.

[0081] In S123, terminal 1 compares frames TR1 and TR2, via the CAL module of the figure 2 .

[0082] If the INF information is present in both the TR1 frame and the TR2 frame, the additional condition of validation of the voluntary approach gesture of the user U is fulfilled. Thus, the terminal 1 can advantageously check whether the TR2 frame resulting from the overmodulation of the envelope of the SGV' signal received in S9 is associated or not with the content of the TR1 frame received.

[0083] In S13, terminal 1 then validates the content of frame TR1 in the conventional manner and then enters into communication either with device 2 if the latter has sufficient management capabilities or with the SG3 management system or any other appropriate management equipment, to activate the service required by terminal 1 (validate the amount of a transaction, validate access to a room, validate a transport ticket balance, etc.).

[0084] If the INF information is only present in frame TR1, the additional condition of validation of the voluntary approach gesture of user U is not met. Terminal 1 therefore does not continue the transaction.

Claims

1. Method for receiving a signal during an intra-body communication via a user (U) carrying a terminal (1), comprising the following, at the level of the terminal: - receiving (S10), from a communication device (2), a signal characterizing the fact that the user has performed an approach gesture towards the device between two times, - detecting (S121), in the received signal, a first radio data frame generated between the two times, said first frame being at the same frequency as that of the received signal, characterized in that it comprises the following, at the level of the terminal: - detecting (S121), in the received signal, a second radio data frame generated between the two times, said second frame being at a frequency different from that of the received signal, - comparing (S122) the first frame with the second frame, - validating (S13) a transaction depending on the presence or absence of information (INF) common to the compared first and second frames.

2. Reception method according to Claim 1, wherein said at least one item of information (INF) common to the first and second frames is an identifier or location information for locating the communication device.

3. Reception method according to Claim 1 or Claim 2, wherein the common information (INF) is represented in binary form.

4. Reception method according to any one of the preceding claims, wherein the second frame is detected multiple times between the two times.

5. Reception method according to any one of the preceding claims, wherein the second frame is detected once between the two times and is representative of the fact that the user has touched the communication device between the two times.

6. Terminal (1) having capabilities for intra-body communication via a user carrying said terminal, said terminal being configured so as to implement the following: - receive, from a communication device, a signal characterizing the fact that the user has performed an approach gesture towards the device, between two times, - detect, in the received signal, a first radio data frame generated between the two times, said first frame being at the same frequency as that of the received signal, said terminal being characterized in that it is furthermore configured so as to implement the following: - detect, in the received signal, a second radio data frame generated between the two times, said second frame being at a frequency different from that of the received signal, - compare the first frame with the second frame, - validate a transaction depending on the presence or absence of information common to the compared first and second frames.

7. Computer program comprising program code instructions for implementing the method for receiving a signal according to any one of Claims 1 to 5 during an intra-body communication via a user (U) carrying a terminal (1) according to Claim 6 when it is executed on said terminal.

8. Computer-readable information medium comprising instructions of a computer program according to Claim 7.

9. Method for transmitting a signal during an intra-body communication via a user (U) carrying a terminal (1), comprising the following, at the level of a communication device (2): - detecting (S5) an approach gesture performed by the user (U) towards the communication device (2), said gesture being performed between two times, - transmitting (S9), to the terminal, a signal characterizing the approach gesture, said signal containing a first radio data frame generated between the two times, said first frame being at the same frequency as that of the transmitted signal, characterized in that said transmitted signal furthermore comprises a second radio data frame generated between the two times, said second frame being at a frequency different from that of the transmitted signal.

10. Transmission method according to Claim 9, wherein said at least one item of information common to the first and second frames is an identifier or location information for locating the communication device.

11. Transmission method according to Claim 9 or Claim 10, wherein the common information is represented in binary form.

12. Transmission method according to the preceding claims, wherein the second frame is generated multiple times between the two times.

13. Transmission method according to the preceding claims, wherein the second frame is generated once between the two times and is representative of the fact that the user has touched the communication device between the two times.

14. Communication device (2) having capabilities for signal transmission during an intra-body communication via a user carrying a terminal, said device being configured so as to implement the following: - detect an approach gesture performed by the user towards the communication device, said gesture being performed between two times, - transmit, to the terminal, a signal characterizing the approach gesture, said signal containing a first radio data frame generated between the two times, said first frame being at the same frequency as that of the transmitted signal, said device being characterized in that said transmitted signal furthermore comprises a second radio data frame generated between the two times, said second frame being at a frequency different from that of the transmitted signal.

15. Computer program comprising program code instructions for implementing the method for transmitting a signal during an intra-body communication via a user (U) carrying a terminal (1) according to any one of Claims 9 to 13 when it is executed on a communication device according to Claim 14.